Although the functional state of the reticuloendothelial system (RES) is known to be affected in circulatory shock, trauma and surgery, very little quantitative work has been done in relation to: a) the exact patterns of RES response in these low-flow states or other stressful states; b) interactions with, or dependencies on, microcirculatory function and integrity; and c) determining whether quantitative RES phagocytic indices may be useful parameters, at a tissue-level, of the progression and response of the shock syndrome to corrective measures. The studies proposed in this project will focus on RES phagocytic function in circulatory shock syndromes and will: 1) Quantify RES response patterns in untreated low-flow states (e.g., hemorrhage, intestinal ischemia, trauma) as well as certain other types of systemic stress, to either survival or death. 2) Determine whether it is feasible and practical to pharmacologically manipulate (acutely and adaptively) simultaneously, the RES and microcirculation with materials compatible for human use. 3) Determine whether sex, sex hormones and genetics are important factors in the RES-shock relationship. 4) Determine the influence of antibiotics on RES function in circulatory shock. 5) Having documented the foregoing as a frame of reference, certain biochemical aspects of RES phagocytic function in circulatory shock will be explored. BIBLIOGRAPHIC REFERENCES: Microcirculation, Vol. 1. Kaley, G. and Altura, B.M. University Park Press, Baltimore, 550 pp., 1977. H1- and H2-histamine receptor antagonists and protection against traumatic shock. Halevy, S. and Altura, B.M. Proc. Soc. Exp. Biol. Med. 154: March, 1977.